From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: Re: [PATCH 26/30] ext4: do not send discards as barriers Date: Mon, 30 Aug 2010 23:02:05 +0200 Message-ID: <20100830210205.GD12226@quack.quadriga.com> References: <1282751267-3530-27-git-send-email-tj@kernel.org> <20100825155842.GA3229@lst.de> <20100825160032.GC3229@lst.de> <4C753D75.2010305@kernel.org> <20100825200223.GE2738@quack.suse.cz> <4C76250B.6060800@kernel.org> <20100827173147.GA12374@quack.suse.cz> <20100830202034.GB12226@quack.quadriga.com> <4C7C170D.9090409@vlnb.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , Jeff Moyer , Tejun Heo , Christoph Hellwig , jaxboe@fusionio.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, linux-raid@vger.kernel.org, James.Bottomley@suse.de, tytso@mit.edu, chris.mason@oracle.com, swhiteho@redhat.com, konishi.ryusuke@lab.ntt.co.jp, dm-devel@redhat.com, rwheeler@redhat.com, hare@suse.de, neilb@suse.de, rusty@rustcorp.com.au, mst@redhat.com, jeremy@goop.org, snitzer@redhat.com, k-ueda@ct.jp.nec.com, Christoph Hellwig To: Vladislav Bolkhovitin Return-path: Content-Disposition: inline In-Reply-To: <4C7C170D.9090409@vlnb.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Tue 31-08-10 00:39:41, Vladislav Bolkhovitin wrote: > Jan Kara, on 08/31/2010 12:20 AM wrote: > >On Mon 30-08-10 15:56:43, Jeff Moyer wrote: > >>Jan Kara writes: > >> > >>> An update: I've set up an ext4 barrier testing in KVM - run fsstress, > >>>kill KVM at some random moment and check that the filesystem is consistent > >>>(kvm is run in cache=writeback mode to simulate disk cache). About 70 runs > >> > >>But doesn't your "disk cache" survive the "power cycle" of your guest? > > Yes, you're right. Thinking about it now the test setup was wrong because > >it didn't refuse writes to the VM's data partition after the moment I > >killed KVM. Thanks for catching this. I will probably have to use the fault > >injection on the host to disallow writing the device at a certain moment. > >Or does somebody have a better option? > > Have you considered to setup a second box as an iSCSI target (e.g. > with iSCSI-SCST)? With it killing the connectivity is just a matter > of a single iptables command + a lot more options. Hmm, this might be an interesting option. Will try that. Thanks for suggestion. Honza -- Jan Kara SUSE Labs, CR